Radio tuner



April 13, 1939- w. J. SCHNELL 2,154,778

RADIO TUNER mp Ma 1N VENTOR.

Jb/mlfi W 11 m w ATTORNEYS;

Patented Apr. 18, 1939 PATENT OFFICE RADIO TUNER William J. Schnell,Berwyn, Ill., auignor to area tricai Research Laboratories Inc.,Chicago, 111.,

a corporation of Illinois Application 111110 16, 1938, Serial No.214,007

9 Claims.

This invention relates to an automatic" radio tuner. and particularly toa radio tuner of the push button type. a

It is an object of applicant's invention to provide a simple, compactand relatively inexpensive tuning device, preferably of the push buttontype, which is readily and precisely adjustable for the selection ofdesired broadcasting stations. It is another object of applicant'sinvention to provide in a radio tuner a plurality of selectivelyenergizable electrical tuning elements or impedances, and to providemeans for controlling the selective energization of said tuning elementsor impedances which last mentioned means shall be individuallyadjustable exteriorly of the radio receiver selectively to vary theimpedance of said tuning elements so that the selected tuning elementwill, whenever energized, tune the receiver to the desired station. 20 Amore specific object of applicant's invention is to provide a tuningdevice comprising a plu-- rality of inductances or condensers whereinmeans is provided for selectively energizing said inductances orcondensers to tune the radio re- 25 ceiver to a selected broadcaststation, and wherein the selected control means is adjustable exteriorlyof the receiver or from the front panel of the receiver by manualmanipulation and without the use of any tool or device to individually30 adjust or pre-set the impedance values of said inductances orcondensers.

Other and further objects and advantages of the invention will beapparent from the following description when taken in connection with 35the accompanying drawings, wherein:

Fig. 1 is a view in elevation of a radio receiver embodying theinvention.

Fig. 2 is a fragmentary horizontal section.

taken substantially along the line 2-2 of Fig. 1. 40 Fig. 3 is a view ofa portion of Fig. 2, but with the elements in a different position ofoperation. Fig. 4 is a fragmentary sectional view taken substantiallyalong the line 4-4 of Fig. 2.

Fig. 5 is an enlarged fragmentary horizontal 45 section on the line H ofFig. 4. Fig. 6 is an enlarged fragmentary section alon the line 68 ofFig. 4.

Fig. '7 is a fragmentary section similar to Fig. 6, but showing amodification. 50 Fig. 8 is a fragmentary horizontal section takensubstantially along the line 8-4 of Fig. I. Fig. 9 is a fragmentarysection similar to Figs. 4 and 7, but showing a second modification.

Fig. 10 is a vertical section along the line ll- 55 ll of Fig. 9.

Fig. 11 is a schematic diagram of the electric circuit for the forms ofFigs. 1 to 6 and Figs. '1 and Fig. 12 is a schematic diagram of thecircuit for the forms of Figs. 9 and 10. 5

As shown in Fig. 1, the radio receiver 2 comprises the usual cabinet 4having a tuning dial 6 over which moves a pointer 8 controlled by theusual manually operable knob iii which also, in the usual manner,controls the tuning adjust- 1 ment of the conventional gang tuningcondenser. The receiver also comprises the usual tone and volumeadjusters l2 and I4 respectively and in addition an automatic tuner iifor automatically adjusting or tuning the receiver to any desired 15 oneof a plurality of selected broadcast stations. The automatic tuner i6preferably comprises a plurality of push buttons l8 located exteriorlyof the front panel of the radio receiver and carried by slidably anddepressibly mounted bars or rods 22 extending through said front panelinto the interior of the receiver.

Each rod 22 interiorly of the receiver is provided with a bifurcatedportion or member 24 formed integrally with or rigidly fastened to the25 rod. The bifurcated member or portion 24 is provided with a centralopening preferably circular in cross section, to receive a sleeve orcollar 26 carried by or secured to the end of a threaded rod 28. Thebifurcated member or portion'24 is 30 slidable upon the sleeve or collar26 which, therefore, acts as a guide for said member, and the sleeve isprovided with a pin 30 received between the furcations of the bifurcatedmember or portion 24 so that the sleeve 26 and rod 28 may be rotated byrotation of the push button i8 and the rod 22. A tube 32, which may beof insulatory material, carries circumferentialiy thereof spacedinduction coils or inductances 34 and 36. The tube 32 is secured to asupporting wall or flange 38 of a bracket 40 welded or otherwisefastened to the front wall 42 of the usual receiver chassis 44. Thissecuring of the tube 32 to the wall or fiange 38 is accomplished by asleeve 46 exteriorly threaded to receive a nut 48 clamping the sleeveagainst the wall or flange 38 and having an enlarged head 50 abuttingthe inwardly extending annular end flange 52 of the tube 32.

The inductivity or inductive value of the coils or inductances 34 and 36is varied or adjustably 50 controlled by integrally connected magneticcores 54 and 56 rigidly secured to the rod 28 within the tube 32. Thesleeve 46 also provides a stationary nut compelling the rod 28 to moveaxially when rotated so as to vary the relative alinement 66 34 and 38,and for this purpose the sleeve 48 is internally threaded to receive theexternal threads of the rod 28. As shown in Fig. 11, there are aplurality of coils or inductances 34 and 38, each pair having theinductive values of its constituent coils controlled by a separate pushbutton I8. One end of each coil 34 (Fig. 11) is connected in common by awire 58, in which is interposed a condenser of the order of .01 of amicrofarad, to the antenna lead 82 which lead is grounded through aresistor 84 of the order of 25,000 ohms. One side of a groundedcondenser 88 of the order of .002 of a microfarad is connected to thecommon wire 58. One unit 88 of the manually adjustable gang condenser I0is connected to the contact 12 of a switch I4 controlling theenergization of a fixed inductance or coil I8. One end of the coil I8 isconnected to the contact 18 of the switch I4 and the other end of saidcoil is connected to the common wire 58. A third contact 80 of theswitch I4 is connected by a lead 82 to a common wire 84 connected to thesignal control grid 88 of a combined amplifier and oscillator vacuumtube 88. The switch 14 is controlled in a manner later to be describedby one of the push buttons I8 and when the coil 18 is energized, thecondenser unit 88 is simultaneously connected therewith and to thecontrol grid 88 so that the receiver may be manually tuned bymanipulation of the control knob I0.

The other end of each of the coils 34 is connected to a contact of aswitch 82, there being one switch 82 for each of the coils 34 and eachof said switches being controlled by one of the push buttons I8. Thecontacts 84 of the switches 82 are connected in common by a wire 88 toone side of a fixed condenser 88 which is grounded at its other side.The other contacts I00 of the switches 82 are connected in common by thecommon wire 84 to the control grid 88 of the amplifying, oscillatingtube 88.

One end of each of the coils 38 is connected by a common wire I02 to theanode electrode I04 of the oscillating section of the tube 88 through acondenser I05 of the order of .002 microfarad. The other end of eachcoil 38 is connected with the contact I08 of a switch I08 controlledsimultaneously with the switch 82. The contact I I0 of each switch I08is connected by a common wire II2 to one side of a fixed condenser II4which is grounded at its other side. The contact II8 of each switch I08is connected by a common wire II8 to the control grid I20 of theoscillator section of the tube 88. A second unit I22 of the manuallyadjusted gang condenser I0 is connected to the contact I24 of a switchI28 controlled simultaneously with the switch 14 by its associated pushbutton III. A fixed inductance or coil I28 is connected at one end tothe common wire I02 and at its other end to the contact I30 of theswitch I28. The third contact I32 of the switch I28 is connected to thecommon wire I I8. A separately adjustable compensating condenser I34 isgrounded at one side and its other side is connected to the common wireI02.

The output of the tube 88 may be fed in any conventional fashion to thesucceeding tubes of the receiver. The usual automatic volume control (A.V. C.) may be connected to the common wire 58 and the source of platepotential for the oscillating section of the tube may be connected tothe common wire I02 between the anode I04 and the condenser I05.

of the cores 54 and 58 with their respective coils All of the switches82, together with switches I4 and I28, are mounted as a unit upon asupport I38 (Fig. 2). The support I38 comprises front and rear platesI38 and I40 respectively and side plates I 42 and I44 respectivelyforming a frame or housing for the switches. The rear frame plate I40 isprovided with inwardly turned upper and lower flanges I48 (Fig. 4) andthe side frame plates I42 and I44 are provided with laterally bentflanges I48 (Fig. 2), the flanges I48 and I48 forming supporting andattaching surfaces for receiving upper and lower insulating plates orsrips I50 and I52 respectively. The contacts 80 and 84 are arranged inpairs on the outer surface of the upper insulating plate. I50 and thecontacts I00 for adjacent ones of the coils 34 are formed as a singleblade secured to the upper surface of the plate I50 between adjacentpairs of the contacts 80 and 84. The contacts I08 and H0 are arranged inpairs and secured to the lower surface of the lower insulating plate I82in the same manner as the contacts 80 and 84 are secured to the upperplate. The contacts I I8 are secured to the lower surface of theinsulating plate I52 and are disposed in a manner similar to thedisposition of the contacts I00 on the plate I50. Amovable switch bladeI54 is adapted to connect each pair of contacts 80 and 84 to theadjacent contact blade I00. The contact blade I 54 comprises a headedportion adapted to bridge the space between the contacts 80 and 84 andan elongated portion in constant engagement with the switch blade I00and adapted to bridge the space between this blade I00 and the contactblade 80 when the blade I 54 is moved to its upper position in Figs. 2and 3 or to its righthand position in Fig. 4. The switch blade I54comprises in addition a depending leg or flange I58 (Fig. 6) extendingthrough a guide slot I58 in the insulating plate I50 and through anopening provided in an insulating plate or strip I80 which is mountedfor slidable movement relative to the plate I50. The lower end of thedepending leg or flange I58 is bent over into clamping engagement withthe lower surface of the slide plate I80 so as to securely fasten themovable switch blade I54 to said slide plate. A similar switch blade I82likewise mounted for slidable movement on the plate I52 is similarlysecured or fastened to an insulating and slidable plate I84 identical tothe slide plate I80. The plates or strips I80 and I84 are carried by aslide bar I 88 to which they are attached by lugs I88 passing throughthe strips I80 and I 84 and by clips I10 bent over the and edges of saidstrips into clamping engagement therewith. Notches I12 are formed in theopposite edges of the slide bar I88 (Fig. 4) to receive the inturnedends of the depending flanges of the switch blades I54 and I82, therebeing suflicient clearance between the walls of these notches and saidinturned ends to prevent engagement between the slide bars and themovable switch blades. The slide bar I88 is formed with a reduced endportion I'I4 received in a guide opening in the rear frame plate I40,and a coiled spring I18 is interposed between said rear frame plate andthe enlarged body portion of the slide bar I 88. The opposite reducedend portion I18 of the slide bar I88 extends forwardly through guideopenings in the front frame plate I44 and the supporting plate 38, andat its forward edge is secured an L- shaped operating bar I80 having abifurcated end portion I82, the furcations of which are received in anannular groove I 84 formed in the rod 22 I 34 and 22.

arse-no oriraithe forwardendofthcbifurcated mamber 'Ihefrontfaceofeachpushbutton I2,exoept one,isasat I22(1'lg.4) toreceiveatabordisk al'ry nllsuitableindicia,suchasthecalilettersofthebroadcaststationforwhiahthe particular push button may be,as setforth,adjustedtotlmethereceiver..

The switch blades or contacts l2, I2, I24 andI22aresecuredtotheinsulating plates I22andI22inamannersimilartothecontacts22,24, I22 and Ill, and the contacts 22and I22 are securedtosaidplatesfnamannersimilartothe contacts I22. Theswitch bladu I4 and I22 are formed similarly to the switch blades I24and I22 and are similarly mounted for slidable movement upon the platesI52 and I22.

The remaining push button I2 is connected, inthesamemannerastheotherbuttonsareconnected. to the switches 22 and I22and to the switches I4 and I22. This push button is also 9 vided with arecess to receive a markingtab indicative of its function, viz., to thetuning device.

A common latch lever or bar I22 extends through enlarged slots I22 inall of the slide bars I22 and through alined slots in the side frameplates I42 and I44. A coiled spring I22 interposed between the sideplate I42 and a washer I24 bolted to the left end of the latch bar I22normally urges said latch bar to the left as seen in Fig. 2. The latchbar I22 is provided with a plurality of latch fingers I22, one for eachof the slide bars I 22 and each adapted to eng e a slot I22 in theassociated slide bar to retain said slide bar in its rearwardlydepressed position. Each latch finger I22 is formed with a cam surface222 having camming engagement with the forward edge of the slot oropening I22.

The adjustment and operation of this form of the invention is asfollows: The adjustable core elements 54 and 56 provide means foradjustably varying the permeability of the cores of the coils In orderto adjust a push button for the selection of a desired station, saidpush button is first depressed to connect the selected coils 24 and 22to the control grids 22 and I22 and to the fixed condensers 22 and H4.The depressed push button I2 is then rotated to rotate the rod 22 andthrough the bifurcated member or portion 24 causes rotation and axialmovement of the rod 22. The axial movement of the rod 22 varies oradjusts the core elements 54 and 52 axially of the coils 24 and 22 andby varying the permeability of the cores, varies the impedance of saidcoils whereby the tuning circuits, of which the selected coils 24 and 22form constituent parts, are adjustably pre-set in frequency so'that thispush button and its operated elements will when operated effect thetuning of the receiver to the desired broadcasting station. Each of thepush buttons I2, other than the push button associated with andcontrolling the switches I4 and I22, is adjusted in like manner topre-set their associated controls to the desired ones of a selectedgroup of broadcasting stations. when it is desired to use an alreadyadjusted button for the selection of a different station, it is merelynecessary to repeat the adjusting operation previously described.

In the form of the invention shown in Figs. 7 and 8, the switch unit 222is mounted within a housing 224 to the rear wall of which is secured thetube 22 in the same manner as said tube is securedtotheplate 22oftheformoftheinventhreadedrodflwhichconholsf the permeability settimofthe adjiutable core 24and22. 'l'heopcratingrodfl'isin upon theinsulating mounting plates I22 and I22. 4

Eachoftherods22'isprovidedwlthafrustoconical cam 2I4 engaged by apivoted latch bar or strip 2I2 common to and extendingtransverselyofallofthe operatingrods 22'. Aspring strip 2I2 the latchbar and normally urga it into latching with the forward face of adepressed cam 2. A coiled spring 222 interposedbetween a partition wall222 and a rear face of the cam normally urges the ted rod 22' to itsforward position. It will be evident that upon depression of theselected rod 22' of the form shown in Fig. 7, the associated switchcontacts 22, 24, I22, I22, Ill and H2 will be operated to connect theselected coils 24 and 22 to the tube 22 and the fixed condensers 22 andH4, and the cam 2, when in its rearward depressed position, will beengaged by the free edge of the latch bar 2I2 and held in said depressedposition. Upon depression of another rod 22', the cam 2 associatedtherewith will cause the latch bar 2I2 to pivot vertically to releasethe cam 2 associated with the previously deprmed rod .and the spring 222will cause said last mentioned rod to move forward into normal position.

It will be seen from the foregoing description that in the forms of theinvention shown in Figs. 1 to 8 and 11, applicant has provided anautomatic permeability tuner embodying a plurality of pre-settabletuning circuits in combination with a manually adjustable tuning circuitand wherein means, such as a plurality of push buttons, are provided fornot only determining the selective connection of a pre-settable tuningcircuit to the signal input of the tube 22, but also for adjusting thecore elements of the coils forming constituent parts of the pre-settabletuning circuits.

In the form of the invention shown in Figs. 9, 10 and 12, the adjustabletuning impedances comprise trimmer condensers of the compressionadjustable type. As shown in Fig. 12, the antenna 224 is coupled by atransformer 222, the secondary 222 of this transformer constituting thefixed inductance common to each of the presettable tuning circuits forthe amplifier portion of the oscillator tube 22. One side of each of theadjustable condensers 222 is connected in common by a wire 222 in whichis interposed a condenser 224, preferably of fixed value to one terminalof secondary 222. The other side of each of the condensers 222 isconnected to a contact 222 of a switch 222, the other contact 242 ofeach of the switches being connected in common by a wire 242 to theother terminal of the secondary winding222andtotheconti'ol8rid22oftheamplifying section of the tube 88. The adjustable unit 244 of themanually adjustable gang .condenser 246 is connected to the common wire232 and by a switch 248 to the common wire 242. The common wire 282 ispreferably grounded as at 258.

The anode electrode I84 of the oscillator section of the tube 88 isconnected by a wire 282 through the primary 254 of the transformer 256to the positive side of the B-supply source. The secondary 258 of thetransformer 256 constitutes the fixed tuning inductance for theoscillator section. One side of each of the trimmer condensers 268 isconnected in common by wire 262, in which is interposed an adjustablecondenser 284 to one terminal of the secondary 258. The other side ofeach of the condensers 268 is connected to the contact 266 of a switch288, and the other contact 218 of each of these switches is connected incommon by a wire 212 to the other terminal of the secondary 258 and tothe control grid I28 of the oscillator section of the tube. Theadjustable unit 214 of the manually adjustable gang condenser 246 isconnected to the common wire 282 and by a switch 216 to the common wire212. The common wire 262 is preferably grounded as at 218.

As shown in Figs. 9 and 10, the trimmer condensers 238 and 268 are ofthe compression adjustable type and are arranged in pairs for commoncontrol by the threaded rod 28 which, similarly to the form of theinvention shown in Figs. 1 to 6, is provided with a sleeve or collar 26slidably received in the bifurcated member or portion 24 carried by orfastened to the rod 22 which latter carries at its outer end the pushbutton I8. The switch unit 288 for selectively controlling theenergization of the condensers 238 and 268 is similar in all respects tothe controlling switch unit in the form of the invention shown in Figs.1 to 6 with the exception that one of the fixed contacts of each ofthese switches is eliminated. The contact which is eliminated may besaid to correspond to the contact 84 of the form shown in Figs. 1 to 6.The slide bar I66 which controls the switch unit 288 has its forwardlyextending reduced end portion I18 pivotally connected as at 282intermediately the ends of a lever 284 pivoted at its upper end to abracket 288 carried by the front wall 288 of a bracket 288. The lowerend of the lever 284 is twisted so as to lie in a plane perpendicular tothe axis of the rod 22 and is bifurcated at its lower edge, thefurcations thereof being received in an angular groove 282 in thebifurcated member or portion 24.

The adjustment and operation of this form of the invention will beapparent from the description hereinabove set forth in respect to theforms of the invention shown in Figs. 1 to 8.

It will be seen from this description that in the form of the inventionshown in Figs. 9, and 12, applicant has provided an automatic tuner ofthe trimmer condenser type embodying a plurality of pre-settable tuningcircuits in combination with a manually adjustable tuning circuit andwherein means, such as a plurality of push buttons, are provided notonly to determine the selective connection of a pre-settable tuningcircuit to the signal member of the tube 88, but also for adjusting thecapacities of the trimmer condensers forming constituent parts of thepre-settable tuning circuits.

Further modifications and changes may be made in the form, constructionand arrangement of the Parts without departing from the spirit of theinvention or sacrificing any of its attendant advantages, and the rightis hereby reserved to make all such changes as fairly fall within thescope of the following claims.

The invention is hereby claimed as follows:

1. In a tuning device for a radio receiver or the like having anamplifier, a plurality of individually tuned circuits, a plurality ofseparate means for connecting each of said tuned circuits to saidamplifier to tune the receiver to a desired station, means forselectively controlling said connecting means, and means operated bysaid control means for varying the tuning of a selected one of saidtuned circuits.

2. In a tuning device for a radio receiver or the like having anamplifier, a plurality of individually tuned circuits comprisinginductances each having an adjustable core. element to vary thepermeability of the core of said inductance whereby to vary theimpedance of said inductance, a plurality of separate means forconnecting each of said tuned circuits to said amplifier to tune thereceiver to a desired station, means for selectively controlling saidconnecting means and means operated by said control means forselectively adjusting the core element of a selected one of said tunedcircuits.

3. In a tuning device for a radio receiver or the like having anamplifier, a plurality of individua'lly adjustable condensers, a commoninductance connected to said amplifier, a plurality of separate meansfor connecting each of said condensers to said inductance and to saidamplifier to tune the receiver to a desired station, means forselectively controlling said connecting means, and means operated bysaid control means for adjusting the selected condenser.

4. In a tuning device for a radio receiver or the like having anamplifier, a plurality of individually tuned circuits, a plurality ofseparate means for connecting each of said tuned circuits to saidamplifier to tune the receiver to a desired station, a plurality of pushbuttons, one for each of said connecting means, for controlling saidconnecting means, and a plurality of separate means each operativelyconnected to one of said push buttons for varying the tuning of aselected one of said tuned circuits.

' 5. In a tuning device for a radio receiver or the like having anamplifier, a plurality of individually tuned circuits comprising aplurality of inductances each having an adjustable core element to varythe permeability of the core of said inductance whereby to vary theimpedance of said inductance, a plurality of separate means forconnecting each of said tuned circuits to said amplifier to tune thereceiver to a desired station, a plurality of push buttons, one for eachof said connecting means, for controlling said connecting means, and aplurality, of separate means each operatively connected to one of saidpush buttons for adjusting the core element of the selected impedance.

6. In a tuning device for a. radio receiver or the like comprising anamplifier, a plurality of individually adjustable condensers, aninductance connected to said amplifier, a plurality of separate meansfor connecting each of said condensers to said inductance and to saidamplifier to tune the receiver to a desired station, a plurality of pushbuttons, one for each of said connecting means, for controlling saidconecting means, and a plurality of separate means each operativelyconnected to one or said push buttons for adjusting the selectedcondenser.

7.1natuningdevicetoraradioreceiverorth like, the combination of aplurality oi pro-settable tuning circuits, an adjustable tuning circuit,a plurality oi. switches for selectively rendering said pre-settabletuning circuits elective to tune the receiver to a desired one of aselected group of broadcast stations, an additional selectively operableswitch, for rendering said adjustable tuning circuit eii'ective to tunethe receiver to any broadcast station, a plurality of push buttons. onefor each of the switches, forcontrolling said switches, and a pluralityof adjusters operatively controlled by said push buttons tor selectivelyvarying the setting or said pre-settable tuning circuits.

8. In a radio receiver or the like having a radio amplifier and anoscillator operatively associated therewith, the combination oiindividually tuned pairs of tuning circuits, a plurality of separate forselectively controlling said connecting means, and means operated bysaid control means for simultaneously varying the tuning of each tunedcircuit 0! the selected pair 01' said circuits.

9. In a tuning device for a radio receiver or the like, the combinationof a plurality oi pre-settable tuning circuits, an adjustable tuningcircult, a plurality oi switches for selectively rendering saidpre-settable tuning circuits eilfective to tune the receiver to adesired one of a selected group of broadcast stations, an additionalselectively operable switch, for rendering said adjustable tuningcircuit effective to tune the receiver to any broadcast station, aplurality of push buttons, one tor each of the switches, for controllingsaid switches, a plurality oi adjusters operatively controlled by saidpush buttons for selectively varying the setting of said pre-settabletuning circuits, automatically operable means for latching the operatedswitch in its operated position and means operatively connected to saidlatching

